Carb Consumption Post-Keto: Sickness And Health Risks?

The ketogenic diet, commonly known as keto, is a low-carb, high-fat diet that switches the body's main fuel source from carbohydrates to fat. While the diet is considered safe for most people, it is associated with some unpleasant side effects, such as nausea, dizziness, sugar cravings, and constipation, among others. This collection of symptoms is often referred to as the keto flu and occurs when the body is deprived of its default energy source, glucose, and has to adapt to burning fat for energy instead. This metabolic process is called ketosis. The keto flu usually lasts for a few days to several weeks, but in extreme cases, it can persist for up to a month.

Carbohydrate intolerance

Disaccharides are normally split into monosaccharides by disaccharidases located in the small bowel. Undigested disaccharides cause an osmotic load that attracts water and electrolytes into the bowel, causing watery diarrhea. Bacterial fermentation of carbohydrates in the colon produces gases (hydrogen, carbon dioxide, and methane), resulting in excessive flatus, bloating, and abdominal pain.

The most common form of carbohydrate intolerance is acquired lactase deficiency (primary adult hypolactasia). Lactase levels are high in neonates, permitting digestion of milk. In most ethnic groups (80% of Black and Hispanic people, and over 90% of Asian people), the levels decrease in the post-weaning period, rendering older children and adults unable to digest significant amounts of lactose. However, 80 to 85% of white people of Northwest European descent produce lactase throughout life and are thus able to digest milk and milk products.

Other common symptoms of carbohydrate intolerance include erectile dysfunction, frequent urinary or vaginal infections, neuropathy (tingling and numbness in your hands and/or feet), weight gain (particularly around the waist), and darker skin around your underarms, neck, and skin folds.

If you are experiencing symptoms of carbohydrate intolerance, it is important to be cautious of your carbohydrate and sugar intake. Even foods that are usually considered “healthy”—like potatoes, oatmeal, and brown rice—can raise your blood sugar and be challenging for those who are carbohydrate intolerant.

If you have been on a keto diet for a while and are experiencing carbohydrate intolerance, it is recommended to slowly reintroduce carbs to help your body readjust. Start with foods that have a low glycemic index and gradually increase your carb intake over time. This will help your body adjust and reduce potential gastrointestinal discomfort.

Keto flu

The keto flu is a collection of symptoms that some people experience when they start a ketogenic diet. It is important to note that this is not an actual flu, and you will not develop a fever. However, the symptoms can be distressing and may include:

• Stomach aches or pains
• Nausea
• Dizziness
• Sugar cravings
• Cramping
• Muscle soreness
• Irritability
• Diarrhea or constipation
• Trouble falling asleep or staying asleep
• Poor focus and concentration
• Brain fog
• Headaches
• Fatigue

The keto flu can last from a few days to several weeks, and in extreme cases, it can last up to a month. The symptoms are caused by your body adapting to a new diet that consists of very few carbohydrates. This is a major change as your body usually burns carbohydrates (glucose) for energy, and switching to burning fat can be a challenge.

• Ease into the diet: Start with a typical low-carb diet and give your body time to adjust before going full keto.
• Stay hydrated: Drink plenty of water to prevent dehydration, which can worsen symptoms like headaches and fatigue.
• Replace electrolytes: Add electrolytes like salts, potassium, and magnesium to your diet. This can help with cramps and nausea.
• Increase healthy fats: Ensure you are consuming enough calories and don't go low-carb and low-fat at the same time. Increasing fat consumption can speed up the transition to burning fat.
• Get plenty of rest: Try an Epsom salt bath to relax your muscles and improve sleep.
• Light exercise: Try restorative yoga to help relieve muscle pain and boost your mood.

How long you've been on keto

How long you've been on the keto diet will affect how eating carbs makes you feel. The longer you've been on keto, the less the carbs will affect you. If you are new to keto and have been eating this way for six weeks or less, there is a good chance that eating any significant amount of carbs will make you feel sick. You may experience nausea, headaches, extreme fatigue, bloating, and even the keto flu. These symptoms occur because your body is not yet fully fat and ketone-adapted. It takes time for your body to build all the metabolic machinery it takes to efficiently use fat and ketones as its primary fuel source.

If you've been eating keto for a couple of months or more, you may not notice any adverse symptoms when you eat carbs. The most common symptom for the average person is fatigue, as your body experiences a rise in blood glucose and insulin, followed by a crash, which it hasn't felt in a while. Your body will adjust, and you won't always feel so tired after eating carbs.

If you've been on keto for a while (say, a year or longer), you may be wondering how long it will take your body to overcome carb sensitivity. Unfortunately, there isn't much literature available on long-term keto diets. Many studies that follow "long-term keto" participants only last about six months. However, for most people, it takes about two weeks to readjust to carbs. This transition period is similar to when you first started keto, so be patient and keep track of how you feel.

Types of carbs consumed

Carbohydrates are essential food nutrients that provide the body with energy. There are three main types of carbohydrates: starches, sugars, and fiber. The body breaks down these carbs into glucose (blood sugar), which is then used as fuel. The amount of carbs consumed affects blood sugar levels. A high intake of carbs can lead to high blood sugar or hyperglycemia, while a low intake can result in hypoglycemia.

When it comes to the types of carbs consumed, it's important to distinguish between simple and complex carbohydrates. Simple carbohydrates are digested quickly and send immediate bursts of glucose into the bloodstream. They include added sugars and naturally occurring sugars. Added sugars are found in sweets, canned fruit, juice, and soda, while naturally occurring sugars are present in fruit and milk. Simple carbs are not inherently bad, but they don't provide the same nourishing effects as complex carbs.

On the other hand, complex carbohydrates are digested more slowly, resulting in a slower release of glucose into the bloodstream. They include fiber and starches, which are found in plant-based foods like fruits, vegetables, and whole-grain products. These complex carbs are recommended as they provide a more stable source of energy and contain essential vitamins, minerals, and fiber.

When reintroducing carbs after a keto diet, it is advisable to start with complex carbohydrates and slowly increase the amount. This helps the body adjust and reduces the risk of digestive issues and other side effects associated with carbohydrate intolerance.

How to reintroduce carbs

General Tips:

• It is important to allow your body to adjust over time. Remember that this is a slow transition, so be patient and keep track of how you feel.
• Since the thing that people tend to miss in a low-carb/keto diet is fiber, slowly reintroducing carbs (especially fiber) is key. This is also helpful for maintaining weight loss since fiber intake is associated with more successful weight loss.
• If you've been on keto for a while (say, one year or longer), it can take about 2 weeks to readjust to carbs. If you've only been on keto for a few days, you may not need as much time to adjust.
• If you experience constipation, increased appetite (to the point of overeating), energy crashes, or other unusual symptoms, ease up on your carb intake.
• Mild bloating or fatigue may last a little longer but will dissipate as your body adjusts.

What to Eat:

• Start with unprocessed carbs. Go for plant-based carbs, whole grains, beans, legumes, fruits, and non-starchy vegetables first, instead of processed foods and sugar-sweetened beverages.
• Choose carbs that are high in protein and fiber. Beans, crackers with seeds, and sprouted breads are all great options that’ll make your transition off keto easier and healthier.
• Reintroduce fruits and vegetables first to make the transition easier. Many fruits and vegetables are high in antioxidants and fiber that will help you stay full as you decrease your intake of fats. Strawberries, carrots, and squash are great fiber-rich options to start with.
• Add more carbs with probiotics to combat bloating. Yogurt and fermented foods, such as miso and sauerkraut, are great options for healthy carbs that contain probiotics that may ease your transition off keto.
• Make lean proteins a staple of your diet. Salmon, turn, turkey, chicken, Greek yogurt, nuts, and eggs are all healthy sources of protein.
• Continue eating healthy fats to combat hunger. It is generally recommended that monounsaturated fats make up 15 to 20% of your diet, polyunsaturated fats make up 5 to 10% of your diet, and saturated fats make up less than 10% each day. Olive oil, nuts, and avocados are all great sources of healthy monounsaturated fats.

What Not to Eat:

• Avoid carbs that are high in sugar. It's best to avoid consuming any sugar-heavy carbs until your body has had at least 2 weeks to adjust. Cookies and donuts can cause your blood sugar to spike, which can make you feel tired and irritable while increasing your sugar cravings.
• Avoid processed oils. These are highly inflammatory because they are damaged in the high heat and pressure processing that it takes to produce them. French fries, tortilla chips, or anything that is breaded and fried may make you feel pretty bad.

Other Tips:

• Eat most of your carbs right before or after exercise. Your body will use the carbs to fuel your work or replenish afterward, which will speed up your metabolism and make them easier to digest.
• Get plenty of sleep to help your body process carbohydrates.
• Meet with a dietitian to help you assess your nutritional needs.

Frequently asked questions